Applications for MPEG transport have appeared that require the substitution of programs within Multiple Program Transport Streams (MPTS) without modification of the Program Specific Information (PSI). One example of such an application is the encoding of security cameras within a multiple dwelling unit (MDU). This analog video is currently being carried within the analog tier of cable television networks; however, these networks are being converted to all digital format which will necessitate the conversion and carriage of these services in digital format. This can be accomplished using existing add-drop methods in unencrypted multiplexes. However, this requires the implementation of the unnecessary processes of de-multiplexing the original MPTS to form Single Program Transport Streams (SPTS), recovery of timing information for each of these streams, dropping the substituted SPTS, and re-multiplexing of the original retained streams along with the substituted streams. For the case of encrypted multiplexes it is not possible to substitute programs within the multiplex due to the fact that necessary timing information is not available in the clear.